JPH114055A - Flexible circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance a flexible circuit board in punchability keeping it high in adhesiveness and dimensional stability by a method wherein a conductor is laminated on the one side of an aromatic polyimide film, which is specified in thickness and relative edge rupture resistance value and lower in volatile matter content than a specific value, directly or through the intermediary of adhesive agent, and then a circuit is formed. SOLUTION: A conductor is laminated, at least, on the one side of an aromatic polyimide film, which is 10 to 125 μm in thickness, of relative edge rupture resistance 22 kg/20 mm/10 μm, and lower than 0.4 wt.% in volatile matter content, directly or through the intermediary of adhesive agent, and a circuit is formed. At this point, the aromatic polyimide film is manufactured through such a manner that 15 mol.% biphenyl tetracarboxylic acid component or aromatic tetracarboxylic acid component which contains its di-anhydride or ester and 5 mol.% aromatic diamine component which contains phenylene diamine are made to react on each other. By this setup, a flexible circuit board of this constitution can be improved in punchability keeping high in adhesiveness and dimensional stability.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
Directly or adhered to at least one side of a punchable aromatic polyimide film having a specific edge resistance of 11 to 22 kg / 20 mm / 10 μm at 25 μm and a volatile content of 0.4% by weight or less. The present invention relates to a flexible circuit board formed by laminating a conductor through an agent and then forming a circuit.

[0002]

2. Description of the Related Art Conventionally, as a flexible circuit board, a conductor layer such as a copper foil is laminated directly or through an adhesive on one or both sides of an aromatic polyimide film.
Generally, a circuit is formed. This aromatic polyimide is a polymer excellent in heat resistance and mechanical properties obtained by heating a polyamic acid produced from a tetracarboxylic acid component and an aromatic diamine component to a high temperature to effect dehydration cyclization. However, the aromatic polyimide film used for the flexible circuit board is required to have higher punchability in order to achieve higher precision and higher productivity.

Japanese Patent Application Laid-Open No. 6-334110 discloses that a polyimide film having an edge crack resistance of 50 to 70 kgf / 20 mm has excellent punching properties.
Further, it is stated that the polyimide film must have some% of a hygroscopic solvent remaining.

In consideration of heat resistance and electrical insulation as an electronic component such as a flexible circuit board, as well as mechanical strength, in particular, high requirements for tensile modulus and low linear expansion coefficient, an aromatic polyimide film is made of tetracarboxylic acid. It is preferable to use a component containing a biphenyltetracarboxylic acid component as a component and a component containing a phenylenediamine component as an aromatic diamine component. Further, in order to form a circuit from a laminate bonded using a metal conductive sheet such as a copper foil and an adhesive, an aromatic polyimide film may be formed using a known polyamide-based adhesive or epoxy. It is necessary to exhibit high adhesiveness to an adhesive such as a resin adhesive or an acrylic resin adhesive.

However, according to the study of the present inventors, the technique described in the above-mentioned Japanese Patent Application Laid-Open No. 6-334110 utilizes a component containing a biphenyltetracarboxylic acid component as a tetracarboxylic acid component, and uses an aromatic diamine component as a component. It has been found that it is not possible to impart satisfactory properties to an aromatic polyimide film produced using a material containing a phenylenediamine component.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a flexible circuit board using an aromatic polyimide film which has good punching properties and maintains adhesiveness and dimensional stability as a substrate film. .

[0007]

According to the present invention, the thickness is 10
To 125 μm, wherein the aromatic polyimide film is 11 to 22 kg / 20 mm
After laminating a conductor directly or via an adhesive on at least one side of an aromatic polyimide film having a specific crack resistance of / 10 μm and a volatile matter content of 0.4% by weight or less, a circuit is formed. The present invention relates to a flexible circuit board formed.

[0008] In this specification, the crack resistance (or specific crack resistance) means the average value of the crack resistance (or specific crack resistance) of samples (5 pieces) measured according to JIS C2318. Specifically, the center line of the V-shaped notch plate test bracket having the upper thickness of 1.00 ± 0.05 mm of the constant-speed tension-type tensile tester was made to coincide with the center line of the upper grip, and the top of the cut and the lower grip were Attach the handle so that the interval is about 30 mm. A test piece with a width of about 20 mm and a length of about 200 mm is passed through the hole of the bracket, folded into two parts, clamped at the lower part of the tester, pulled at a speed of about 200 mm per minute, and pulled apart. Is called end tear resistance.
Five test pieces were taken from the longitudinal direction and the lateral direction over the entire width, respectively, and the average value of the end crack resistance was determined and shown as the end crack resistance value. The specific tear resistance is a tear resistance per film thickness (converted to 10 mm).

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The main preferred embodiments of the present invention are listed below. 1) At least 15 mol% of the aromatic polyimide film
The above flexible circuit board comprising a polyimide produced by reacting an aromatic tetracarboxylic acid component containing biphenyltetracarboxylic acid or a dianhydride or an ester thereof with an aromatic diamine component containing at least 5 mol% of phenylenediamine. . 2) The specific tear resistance of the aromatic polyimide film is 11 to 11
The above flexible circuit board in the range of 15 kg / 20 mm / 10 μm. 3) The volatile matter content of the aromatic polyimide film is 0.1
The above-mentioned flexible circuit board having -0.35% by weight, particularly 0.1-0.3% by weight, and especially 0.1-0.2% by weight. 4) The flexible circuit board as described above, wherein the layer containing at least one surface of the aromatic polyimide film further contains 0.1 to 3% by weight of an inorganic filler. 5) The flexible circuit board as described above, wherein the surface of the aromatic polyimide film has been subjected to any one or more of surface treatment treatment, corona discharge treatment, flame treatment, ultraviolet irradiation, glow discharge treatment, and plasma treatment. 6) The water absorption of the aromatic polyimide film is 0.5-1.
8%, a tensile modulus of 450-1000 kg / mm ² and a coefficient of linear expansion (50-200 ° C.) of 0.6 × 10 ⁻⁵ −
The above flexible circuit board having a ^{density of} 2.5 × 10 ⁻⁵ cm / cm / ° C. or less. 7) Dielectric breakdown voltage of aromatic polyimide film is 3KV
The volume resistivity (25 ° C.) is 1 × 10 ¹⁵ Ω ·
cm or more. 8) The flexible circuit board as described above, wherein the adhesive is a thermoplastic adhesive or a thermosetting adhesive. 9) The adhesive is polyimidesiloxane-epoxy resin-
The above flexible circuit board, which is a thermosetting adhesive having a high heat resistance and a low dielectric property of an epoxy curing agent. 10) The adhesive, wherein the adhesive is provided by applying an adhesive solution to the aromatic polyimide film and then dried, or the adhesive provided by bonding the adhesive provided on the protective film to the aromatic polyimide film. Flexible circuit board.

As the above-mentioned biphenyltetracarboxylic acid component, for example, 3,3 ', 4,4'-biphenyltetracarboxylic acid, dianhydride or ester thereof can be used. , 4,4'-biphenyltetracarboxylic dianhydride is preferably used.

The aromatic tetracarboxylic acid component further includes pyromellitic dianhydride, 3,3 ', 4,4'
-Benzophenonetetracarboxylic dianhydride, 2,
2 ', 3,3'-benzophenonetetracarboxylic dianhydride, 2,2-bis (3,4-dicarboxyphenyl)
Propane dianhydride, 2,2-bis (2,3-dicarboxyphenyl) propane dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, bis (2,3-dicarboxyphenyl) ) Ether dianhydride, 2,3,6
7-naphthalenetetracarboxylic dianhydride, 1,4
5,8-naphthalenetetracarboxylic dianhydride, 1,
2,5,6-naphthalenetetracarboxylic dianhydride,
2,2-bis (3,4-dicarboxyphenyl) -1,
1,1,3,3,3-hexafluoropropane dianhydride, 2,2-bis (2,3-dicarboxyphenyl)
Also included are 1,1,1,3,3,3-hexafluoropropane dianhydride and the like.

The above phenylenediamine may be any of o-phenylenediamine, m-phenylenediamine and p-phenylenediamine. Aromatic diamine components that can be used in combination with phenylenediamine include diaminodiphenyl ether, 4,4′-diaminodiphenylpropane, 4,4′-diaminodiphenylethane,
4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfide, bis [4- (4-aminophenoxy) phenyl] methane, 2,2-bis [4- (4
-Aminophenoxy) phenyl] propane, 2,2'-
Bis [4- (aminophenoxy) phenyl] -1,1,
1,3,3,3-hexafluoropropane, bis [4-
(4-aminophenoxy) phenyl] ether and the like.

In the present invention, the aromatic polyimide film (or the surface-treated film) has a thickness of 1%.
It is preferably from 0 to 125 μm, particularly preferably from 25 to 75 μm, and particularly preferably from 45 to 55 μm. When the thickness of the aromatic polyimide film is smaller than the lower limit, the self-supporting property is low. When the thickness is larger than the upper limit, a large cost is required for production. On the other hand, if the volatile matter content is more than 0.4% by weight, problems occur in the adhesiveness and dimensional stability. If the specific crack resistance of the aromatic polyimide film is outside the above range, the object of the present invention cannot be achieved.

When (1) the water absorption and (2) the coefficient of linear expansion (50 to 200 ° C.) are within the above ranges, the dimensional stability under various environments (high temperature, etching, etc.) is good. It is. Further, (3) when the tensile modulus is in the above range, the handling is good as a substrate film.

The aromatic polyimide film according to the present invention can be manufactured, for example, as follows.
Preferably first the tetracarboxylic dianhydride, preferably biphenyltetracarboxylic acids and phenylenediamine,
Preferably, paraphenylenediamine is polymerized in an organic polar solvent usually used for the production of a polyimide such as N, N-dimethylacetamide or N-methyl-2-pyrrolidone, preferably at 10 to 80 ° C. for 1 to 30 hours. And the polymer
Logarithmic viscosity (measuring temperature: 30 ° C., concentration: 0.5 g / 10
0 ml solvent, solvent: N-methyl-2-pyrrolidone) 0.1-5, polymer concentration 15-25% by weight, rotational viscosity (30 ° C.) 500-4500 poise polyamic acid (imidization) (Rate: 5% or less) to obtain a solution.

Next, preferably, the polyamic acid 10
0.01 to 1% by weight, based on 0 part by weight, of a phosphorus compound, for example an organic phosphorus-containing compound such as a (poly) phosphate ester and / or an amine salt of a phosphate ester or an inorganic phosphorus compound, and preferably further a polyamic acid Acid 10
0.1 to 3 parts by weight of an inorganic filler such as colloidal silica, silicon nitride, talc, titanium oxide, potassium phosphate or the like (preferably 0.005 to 5 μm)
m, especially 0.005 to 2 μm) to prepare a polyamic acid solution composition. These phosphorus compounds and / or inorganic fillers may be uniformly present in the entire film layer, or when forming a film having a two- or three-layer structure, the phosphorus compound and / or the inorganic filler are contained in the layer containing at least one surface in the above ratio. Let it.

The polyamic acid solution composition is cast on a glass or metal support having a smooth surface to form a thin film of the solution, and when the thin film is dried,
Adjust the drying conditions (preferable temperature: 100 to 16
(0 ° C., time: 1 to 60 minutes) By drying, the solidified film has a volatile content of 25 to 50% by weight and an imidization rate of 5 to 60% in the solidified film. A solidified film is formed, and the solidified film is peeled from the support surface.

Next, after one or both surfaces of the solidified film are coated with a surface treating solution containing an aminosilane-based, epoxysilane-based or titanate-based surface treating agent, the film can be further dried. As the surface treatment agent, γ-
Aminopropyl-triethoxysilane, N-β- (aminoethyl) -γ-aminopropyl-triethoxysilane, N- (aminocarbonyl) -γ-aminopropyl-
Triethoxysilane, N- [β- (phenylamino)-
Ethyl] -γ-aminopropyl-triethoxysilane,
Aminosilanes such as N-phenyl-γ-aminopropyl-triethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-phenylaminopropyltrimethoxysilane, and β- (3,4-epoxycyclohexyl)- Epoxysilanes such as ethyl-trimethoxysilane and γ-glycidoxypropyl-trimethoxysilane; and titanates such as isopropyl-tricumylphenyl-titanate and dicumylphenyl-oxyacetate-titanate. And other heat-resistant surface treatment agents. The surface treatment liquid is 0.5 to 5
It can be used as a solution of an organic polar solvent such as a lower alcohol or amide solvent containing 0% by weight. The surface treatment liquid is preferably applied uniformly using a gravure coating method, a silk screen, a dipping method or the like to form a thin layer.

One example of the method for producing an aromatic polyimide film according to the present invention will be described below with reference to FIG. 1, which shows preferable heating conditions before curing in a curing furnace. That is, the solidified film obtained as described above is further dried if necessary, and preferably the volatile content of the dried film is adjusted to 10 to 45% by weight, and then the width of the dried film is adjusted. Fig. 1
Temperature (° C) (preferably 100 to 250 ° C) at the entrance of the curing furnace in the curing furnace shown in (1) x residence time (minutes)
After drying so that is within the range of the oblique line, the maximum heating temperature: 4
The dried film is heated and dried and imidized under the condition that the temperature is from 00 to 500 ° C. for 0.2 to 30 minutes. It can be suitably manufactured as a polyimide film. After the curing step, one or both sides of the aromatic polyimide film are alkali-treated (for example, immersed in an aqueous solution of sodium hydroxide or an aqueous alkali solution such as potassium hydroxide / hydrazine hydrate), washed with water and dried. By applying the above-mentioned surface treatment liquid and drying it, the film surface can be similarly surface-treated.

The aromatic polyimide film obtained as described above is preferably used under low tension or no tension.
Heat at a temperature of about 00 to 400 ° C. to perform stress relaxation treatment,
Take up.

In the above-mentioned aromatic polyimide film, the heating conditions before curing in the curing furnace during the above-mentioned production are controlled within the range shown in FIG. 1 and the curing conditions are adjusted to the above-mentioned temperature and time. When the thickness is in the range, the thickness is 10 to 125 μm, the volatile matter content is 0.4% by weight or less, and the specific crack resistance is set to the value specified in the present invention. it can.

The aromatic polyimide film according to the present invention preferably has 3,3 as a tetracarboxylic dianhydride.
It can be easily obtained by a method of polymerizing 3 ′, 4,4′-biphenyltetracarboxylic dianhydride and paraphenylenediamine as an aromatic diamine, but as a polyamic acid, it satisfies the physical properties of the film. Within the range, other components may be polymerized together with 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and paraphenylenediamine, and the type of bond may be random polymerization or block polymerization. Any of them may be used. Also,
If the total amount of each component in the finally obtained polyimide film is within the above range, polyamic acid containing 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and paraphenylenediamine are included. You may mix and use the polyamic acid component which consists of another component with polyamic acid. In either case, the polymer is cut and recombined at the time of heating at a high temperature, and the target aromatic polyimide film can be obtained in the same manner as described above. Further, the aromatic polyimide film in the present invention is not limited to the above-mentioned thermal imidization, and can be similarly performed by chemical imidization within the above-mentioned conditions.

The aromatic polyimide film in the present invention is preferably subjected to a surface treatment by a corona discharge treatment, a plasma treatment, an ultraviolet irradiation, a glow discharge treatment, and a flame treatment, as it is or when it is not treated with a surface treatment agent. After that, an adhesive layer can be provided by applying an adhesive or laminating films of these adhesives.

As a method for laminating a conductor layer on the surface of the aromatic polyimide film, preferably a film-treated surface, a conductor layer may be directly laminated by a vapor deposition method, a sputtering method, a plating method, or an adhesive layer. The conductor layer may be laminated via an agent.

The adhesive for laminating the conductor layers via the adhesive may be thermosetting or thermoplastic as long as it has heat resistance. For example, epoxy resin, NBR-phenol-based resin, phenol-butyral-based resin, epoxy-NB
R resin, epoxy-phenol resin, epoxy-nylon resin, epoxy-polyester resin, epoxy-acrylic resin, acrylic resin, polyamide-epoxy-phenol resin, polyimide resin, polyimide siloxane -Thermosetting adhesives such as epoxy resins,
Alternatively, a thermoplastic adhesive such as a polyamide resin, a polyester resin, a polyimide resin, and a polyimidesiloxane resin may be used. The thickness of this adhesive is 5-35μ
m is preferable. In particular, a polyimide adhesive (preferably a heat-fusible non-crystalline polyimide, in which non-crystalline is substantially non-crystalline when analyzed by the Leuland method for an X-ray diffraction spectrum, preferably Has a crystallinity of less than 10%, especially 3% or less, and among them, 1%
The following are preferred. Glass transition temperature: Tg
Is preferably about 180 to 260 ° C. ],
Polyimide siloxane-epoxy resin adhesive [Polyimide siloxane is preferably a polyimide siloxane having a reactive group with the epoxy resin. Usually, an epoxy curing agent is blended. Preferably polyimide siloxane 10
5-200 parts by weight of an epoxy resin and 0-150 parts by weight of an epoxy curing agent and optionally 0-20 parts by weight of a curing catalyst per 0 parts by weight. It is known that it has high heat resistance and low dielectric properties. ), An epoxy resin adhesive is preferably used. Further, the adhesive may contain an inorganic filler. This adhesive may be provided by applying an adhesive solution to the aromatic polyimide film and then drying, or may be provided by bonding the adhesive provided on the protective film to the aromatic polyimide film.

The conductor in the present invention includes metals such as aluminum, copper, and copper alloy, and copper foil is preferably used. As copper foil, there are electrolytic copper foil and rolled copper foil,
Those having a tensile strength of 17 kg / mm ² or more are preferred. Further, the thickness is preferably 8 to 50 μm.

A circuit is formed on the aromatic polyimide film according to the present invention after a conductor is laminated directly or, preferably, via an adhesive. When a circuit is formed on a conductor, the conductor is laminated on the aromatic polyimide film directly or via an adhesive to produce a conductive substrate, and then, for example, an etching resist is applied on the surface of the conductor with a circuit pattern. After forming a wiring pattern of an etching resist for protecting the surface of the conductor at the portion where the wiring pattern is formed, the wiring pattern is printed in a shape (wiring pattern shape), and then etched by a method known per se. The etching can be performed by removing a portion of the conductor where no wiring is formed by etching using an etching solution and removing an etching resist. A coat layer may be formed by directly coating the upper surface of the circuit pattern or by treating it with a surface treating agent such as a silane coupling agent, applying a coating material (liquid material), and drying by heating.

[0028]

Embodiments of the present invention will be described below. In each of the following examples, the physical properties of the polyimide film were measured by the following methods. Water absorption: measured according to ASTM D570-63 (23
° C × 24 hours) Tensile modulus: Measured according to ASTM D882-64T (MD) Coefficient of linear expansion (50 to 200 ° C): A sample that has been heated at 300 ° C for 30 minutes and stress-relaxed is subjected to a TMA apparatus (tensile module).
(2g load, sample length 10mm, 20 ° C / min)

The imidization ratio: calculated from the ratio of absorbance at 1780 cm ^-1 and 1510 cm ^-1 by FI-IR (ATR method). The measurement was performed on the A side of the film. Volatile content (solidified film): determined by the following equation. Volatile content (solidified film) = [(AB) / A] x
100 A: Film weight before heating B: Film weight after heating at 420 ° C. for 20 minutes Volatile content (polyimide film): determined by the following formula. Volatile content (polyimide film) = [(AB) /
A] × 100 A: Weight after drying at 150 ° C. × 10 minutes B: Weight after drying at 450 ° C. × 20 minutes (Normally tested in air, but if deteriorated by high temperature heating in air, nitrogen gas Test in)

Dielectric breakdown voltage: ASTM D149-64
(25 ° C.) Volume resistivity: measured according to ASTM D257-61 (25 ° C.) Dielectric constant: measured according to ASTM D150-64T (2
(5 ° C., 1 KHz) Peel strength: 180 ° peel strength, 50 mm / min

Example 1 54.6 kg of N, N-dimethylacetamide was added to a polymerization tank having an internal volume of 100 liters.
4,4'-biphenyltetracarboxylic dianhydride 8.8
26 kg and 3.243 kg of paraphenylenediamine are added and polymerized at 30 ° C. for 10 hours, and the logarithmic viscosity of the polymer (measuring temperature: 30 ° C., concentration: 0.5 g / 100 ml solvent, solvent: N, N-dimethyl) Acetamide)
Was 1.60, and a polyamic acid (imidization ratio: 5% or less) solution having a polymer concentration of 18% by weight was obtained. In this polyamic acid solution, monostearyl phosphate triethanolamine salt at a ratio of 0.1 part by weight to 100 parts by weight of the polyamic acid and an average particle diameter of 0 part by weight (based on solid content) of 0.5 part by weight. 0.08 μm of colloidal silica was added and uniformly mixed to obtain a polyamic acid solution composition. The rotational viscosity of this polyamic acid solution composition was 30.
It was 00 poise. This polyamic acid solution composition was continuously cast from a slit of a T-die mold.
The solution was extruded on a smooth support in a drying furnace to form a thin film of the solution, and dried at an average temperature of 141 ° C. to form a long solidified film. By peeling from the surface of the support, a long solidified film was obtained. Next, an aminosilane surface treatment solution of N, N-dimethylacetamide was uniformly applied to both surfaces of the long solidified film, and then dried to obtain a dried film having a surface treated. This dried film had a volatile content of 27% by weight consisting of a solvent and produced water. Next, the dried film subjected to the surface treatment is cured in a curing furnace while holding the width direction of the dried film (temperature at the inlet × residence time =
240 ° C x 2 minutes, maximum temperature x maximum temperature residence time = 480
° C × 1 minute), both sides treated with a surface treatment agent, thickness 25 μm
Was continuously produced. Table 1 shows the results of measurement and evaluation of this aromatic polyimide film. A thermosetting adhesive (comprised of cresol novolak resin, epoxy resin, polyvinyl butyral and imidazole) is applied on the above-mentioned aromatic polyimide film (one side), and the applied thickness after drying is 20 μm.
Apply and dry so that Next, an electrolytic copper foil (35 μm) was roll-laminated (about 1 second) at 130 ° C. and 2 kg / cm ^{2 on} the surface of the adhesive, and bonded. Then, the bonded product was treated at 100 ° C. for 2 hours and at 120 ° C. for 1 hour for 18 hours.
The adhesive was cured by heating at 0 ° C. for 6 hours to obtain a laminate. Subsequently, patterning was performed on the copper-clad laminate, which is a laminate, in accordance with a conventional method, followed by etching, washing and drying steps, and then coating and drying a coating material to produce a flexible circuit board.

Example 2 An elongated solidified film was obtained in the same manner as in Example 1, except that the slit width of the T-die was changed. The dried film was obtained by heating and drying in the same manner as in Example 1 without applying the surface treatment liquid to both surfaces of the long solidified film. This film had a volatile content of 27% by weight. Then, while holding the dried film in the width direction, it is cured in a curing furnace (temperature at the entrance × residence time = 200 ° C. × 4 minutes, maximum temperature × maximum temperature residence time = 480 ° C. × 3 minutes), Thickness 50
A long aromatic polyimide film having a length of μm was continuously produced. Measurement and measurement of this aromatic polyimide film
Table 1 shows the results of the evaluation. A flexible circuit board was manufactured in the same manner as in Example 1 using a film obtained by subjecting the aromatic polyimide film to low-temperature plasma treatment by a conventional method (the same physical properties as those of the film before treatment).

Example 3 A long solidified film was produced in the same manner as in Example 2. Next, a dried film surface-treated in the same manner as in Example 1 was obtained. This film had a volatile content of 28% by weight. Next, while holding the dried film in the width direction, it is cured in a curing furnace (temperature at the inlet × residence time = 200 ° C. × 2.5 minutes, maximum temperature × maximum temperature residence time = 480 ° C. × 3 minutes) ), A long aromatic polyimide film having a thickness of 50 µm and having both surfaces treated with a surface treating agent was continuously produced. Table 1 shows the results of measurement and evaluation of the aromatic polyimide film. Using this aromatic polyimide film, a flexible circuit board was manufactured in the same manner as in Example 1.

Example 4 An elongated solidified film was obtained in the same manner as in Example 2 except that the slit width of the T-die was changed. Next, a dried film without surface treatment was obtained in the same manner as in Example 2. This film had a volatile content of 30% by weight. Next, while holding the dried film in the width direction, the dried film is cured in a curing furnace (temperature at the inlet × residence time = 140 ° C. ×
5 minutes, maximum temperature x maximum temperature residence time = 480 ° C x 3
Min), a long aromatic polyimide film having a thickness of 75 μm was continuously produced. Both surfaces of the aromatic polyimide film were alkali-treated (immersed in a solution of potassium hydroxide / hydrazine hydrate / water for 3 minutes, then washed with acid, washed with water, and dried), and subjected to surface treatment in the same manner as in Example 1. Then, a long aromatic polyimide film having a thickness of 75 μm, both surfaces of which were treated with a surface treating agent, was continuously produced. Table 1 shows the results of measurement and evaluation of the aromatic polyimide film. Using this aromatic polyimide film, a flexible circuit board was manufactured in the same manner as in Example 1.

Example 5 A long solidified film was obtained in the same manner as in Example 2 except that the slit width of the T-die was changed. A dried film was obtained by heating and drying in the same manner as in Example 2 without applying the surface treatment liquid to both surfaces of the long solidified film. This film had a volatile content of 30% by weight. Then, while holding the dried film in the width direction, the film is cured in a curing furnace (temperature at the inlet × residence time = 105 ° C. × 9 minutes, maximum temperature × maximum temperature residence time = 450 ° C. × 15 minutes), Thickness 7
A 5 μm long aromatic polyimide film was continuously produced. Table 1 shows the results of measurement and evaluation of the aromatic polyimide film. A flexible circuit board was manufactured in the same manner as in Example 2 using a film (the physical properties were the same as the film before the treatment) which had been subjected to low-temperature plasma treatment by a conventional method using this aromatic polyimide film. The heat shrinkage of the aromatic polyimide film in Examples 1 to 5 (250 ° C., 2 hours, JIS C2318)
Were all 0.3% or less.

Example 6 The film portion of the flexible circuit board obtained in Examples 1 to 5 was punched out with a mold and the cut surface was observed. The case where the linearity was maintained and generation of beards and debris was not observed is indicated by ○, and the case where linearity was poor and generation of beards and debris was observed is indicated by ×. The results are summarized in Table 1.

[0037]

[Table 1]

Example 7 Production of polyimidesiloxane-1 According to the method described in JP-A-5-25453, it was produced as follows. In a 2-liter glass separable flask, N-methyl-2-pyrrolidone (NM
P) Using 1,000 g as a solvent, 2,3,3 ′, 4′-biphenyltetracarboxylic dianhydride (a-BPDA) 7
3.56 g (250 mmol) of diaminopolysiloxane [2 HN-C3 H6- (Si (CH3) 2 O) n-S
i (CH3) 2-C3 H6-NH2, n = 9.5] 88 g
(100 mmol) and 61.58 g of 2,2-bis [4- (4-aminophenoxy) phenyl] propane (150
Was polymerized and imidized, and then poured into a large amount of water and dried to obtain 210 g of a polyimidesiloxane (polyimidesiloxane-1) powder. This polyimide siloxane had a logarithmic viscosity (30 ° C.) of 0.32. Further, a film prepared from a solution of this polyimidesiloxane powder in tetrahydrofuran has a tensile modulus of 5%.
7 kg / mm ² , Tg (glass transition temperature) 190 ° C
And the crystallinity was 0%.

Production of Flexible Circuit Board As the thermosetting adhesive, 50 parts of the above-mentioned polyimide siloxane (polyimide siloxane-1) and 15 parts of an epoxy resin (trade name: Epicoat 807, manufactured by Yuka Shell Co., Ltd.)
Part, epoxy resin (Sumitomo Chemical Co., Ltd., trade name: ELM1)
00) 6 parts, a resin mixture consisting of 17 parts of a phenol novolak resin (Meiwa Kasei Co., H-5) as a curing agent and 0.1 part of 2-phenylimidazole as a curing catalyst (dissolved in 250 parts of tetrahydrofuran) And an aromatic polyimide film having a thickness of 50 μm obtained without plasma treatment (specific edge resistance: 13.9 kg / 20 mm / 10
μm, volatile content: 0.13%, water absorption: 1.3%,
Tensile modulus: 865 kg / mm ² , coefficient of linear expansion: 1.1
× 10 ⁻⁵ / ° C., dielectric breakdown voltage: 10.3 kv, volume resistivity: 4.7 × 10 ¹⁶ Ω · cm, dielectric constant: 3.2) Thus, a flexible circuit board was obtained. Evaluation was performed in the same manner as in Example 2 and Example 6, and the peel strength (kg / cm, 180 °) of the laminate was 2.
A result of 4 kg / cm and good punchability was obtained.

Example 8 Preparation of polyimide siloxane-2 In a 2 liter glass separable flask, N
Using 1,000 g of -methyl-2-pyrrolidone (NMP) as a solvent, 73.56 g (250 mmol) of 2,3,3 ', 4'-biphenyltetracarboxylic dianhydride (a-BPDA) and diaminopolysiloxane [2 HN-C3H
6-(Si (CH3) 2O) n-Si (CH3) 2-C3H
6-NH2, n = 9.5] 121.4 g (138 mmol) and 2,2-bis [4- (4-aminophenoxy) phenyl] propane 41.05 g (100 mmol)
After polymerization and imidation of 3.58 g (12.5 mmol) of bis (3-carboxy-4-aminophenyl) methane, the mixture was poured into a large amount of water and dried to obtain polyimide siloxane (polyimide siloxane-1). 210 g of powder
I got This polyimide siloxane has a logarithmic viscosity (30
° C) was 0.32. The film prepared from this polyimidesiloxane powder in tetrahydrofuran solution had a tensile modulus of 20 kg / mm ² and a Tg (glass transition temperature) of 110 ° C.

Production of Flexible Circuit Board As the thermosetting adhesive, 50 parts of the above-mentioned polyimide siloxane (polyimide siloxane-2) and epoxy resin (trade name: Epicoat 807, manufactured by Yuka Shell Co., Ltd.)
Part, epoxy resin (Sumitomo Chemical Co., Ltd., trade name: ELM1)
00) 6 parts, phenol-novolak resin (Meiwa Kasei Co., Ltd.)
H-5) A flexible circuit board was obtained in the same manner as in Example 7, except that 17 parts and 0.1 part of 2-phenylimidazole as a curing agent were dissolved in 250 parts of tetrahydrofuran. . Evaluation was performed in the same manner as in Example 2 and Example 6, and the peel strength (kg / cm, 1
80 °) of 2.3 kg / cm and good punching properties.

Example 9 A flexible circuit board was obtained in the same manner as in Example 7, except that the applied thickness of the thermosetting adhesive after drying was 5 μm, and that the thickness of the electrolytic copper foil was 12 μm. Was. Evaluation was performed in the same manner as in Example 2 and Example 6, and the peel strength (kg / cm, 180 °) of the laminate was 2.0 kg / cm,
The result that the punching property was good was obtained.

Example 10 An adhesive obtained by adding 50 parts of alumina nitride (manufactured by Tokuyama, specific surface area: 2.72 m ² / g) to the thermosetting adhesive of Example 7 was used. A flexible circuit board was obtained in the same manner as in Example 7. Evaluation was performed in the same manner as in Examples 2 and 6, and the peel strength (kg / c
m, 180 °) was 1.5 kg / cm, and the result was that the punching property was good.

Example 11 The thermosetting adhesive solution prepared in Example 7 was applied to a polyethylene terephthalate (PET) film (thickness: 25 μm).
m) was applied and dried so that the applied thickness after drying was 20 μm, and a PET film was adhered to both sides of the adhesive. Next, one of the PET films of the adhesive sheet was peeled off, and the surface of the adhesive was aligned on the aromatic polyimide film produced in Example 2 at 130 ° C. The other PET film on the adhesive was peeled off, an electrolytic copper foil was stuck on the adhesive in the same manner as in Example 2, and a flexible circuit board was obtained in the same manner as in Example 2. Evaluation was performed in the same manner as in Example 2 and Example 6,
The peel strength (kg / cm, 180 °) of the laminate is 2.3k
g / cm and good punchability were obtained.

Example 12 A solution of the polyimidesiloxane (polyimidesiloxane-1) in tetrahydrofuran obtained in Example 7 was applied and dried on an aromatic polyimide film so that the applied thickness after drying was 20 μm. In the same manner, a solution of polyimidesiloxane in tetrahydrofuran was applied to the opposite surface of the film and dried to obtain a film in which a thermoplastic adhesive was applied to both surfaces. It was confirmed that the film coated with the adhesive on both sides can be used as a tape for LOC (lead-on-chip). That is, the electrolytic copper foil was laminated on both sides of the film with the adhesive on both sides, and the electrolytic copper foil was laminated in the same manner as in Example 2 except that the lamination temperature with the copper foil was set to 200 ° C. A flexible circuit board was obtained. Evaluation was performed in the same manner as in Example 2 and Example 6, and the peel strength (kg / cm, 1
80 °) was 1.8 kg / cm, and the result was that the punching property was good.

[0046]

Since the present invention is configured as described above, the following effects can be obtained. ADVANTAGE OF THE INVENTION The flexible circuit board of this invention has favorable punching property, and also maintains adhesiveness, and can process with high precision.

[Brief description of the drawings]

FIG. 1 shows a range of suitable heating conditions before curing in a curing furnace in an example of a method for producing an aromatic polyimide film according to the present invention. Vertical axis Temperature at the entrance of cure furnace (° C) × Residence time (minutes) Horizontal axis Film thickness (μm) Oblique line Preferred range

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08G 73/10 C08G 73/10 H05K 3/38 H05K 3/38 E

Claims (15)

[Claims] 1. The method according to claim 1, wherein the thickness is 10 to 125 μm, and
A conductor was laminated directly or via an adhesive on at least one surface of an aromatic polyimide film having a specific crack resistance of ２２22 kg / 20 mm / 10 μm and a volatile matter content of 0.4% by weight or less. Later, a flexible circuit board on which a circuit is formed. 2. An aromatic polyimide film comprising: an aromatic tetracarboxylic acid component containing at least 15 mol% of biphenyltetracarboxylic acid or a dianhydride or an ester thereof; and an aromatic diamine component containing at least 5 mol% of phenylenediamine. 2. The flexible circuit board according to claim 1, comprising a polyimide produced by the reaction with: 3. The flexible circuit board according to claim 1, wherein the specific crack resistance of the aromatic polyimide film is in a range of 11 to 15 kg / 20 mm / 10 μm. 4. A method according to claim 1, wherein the aromatic polyimide film has a volatile matter content of 0.1 to 0.35% by weight.
The flexible circuit board as described. 5. The flexible circuit board according to claim 1, wherein the layer containing at least one surface of the aromatic polyimide film contains 0.1 to 3% by weight of an inorganic filler. 6. The surface of the aromatic polyimide film is treated with a surface treatment agent, corona discharge treatment, flame treatment, ultraviolet irradiation,
The flexible circuit board according to any one of claims 1 to 5, wherein at least one of a glow discharge treatment and a plasma treatment is subjected to a surface treatment. 7. The aromatic polyimide film has a water absorption of 0.5 to 1.8% and a tensile modulus of 450 to 1000 kg.
/ Mm ² and a coefficient of linear expansion (50 to 200 ° C.) of 0.
The flexible circuit board according to claim 1, wherein the flexible circuit board has a temperature of 6 × 10 ⁻⁵ −2.5 × 10 ⁻⁵ cm / cm / ° C. 8. 8. The aromatic polyimide film has a dielectric breakdown voltage of 3 KV or more and a volume resistivity (25 ° C.) of 1 ×.
The flexible circuit board according to claim 1, wherein the flexible circuit board has a resistance of 10 ¹⁵ Ω · cm or more. 9. The flexible circuit board according to claim 1, wherein the adhesive is a thermoplastic adhesive or a thermosetting adhesive having a thickness of 5-35 μm. 10. The adhesive according to claim 9, wherein the adhesive is a thermoplastic or thermosetting adhesive containing an inorganic filler in a proportion of 0 to 50 parts by weight based on 100 parts by weight of the adhesive resin.
4. The flexible circuit board according to claim 1. 11. The flexible circuit board according to claim 9, wherein the adhesive is a thermoplastic adhesive made of a heat-fusible amorphous polyimide. 12. The flexible circuit board according to claim 11, wherein the adhesive is a high heat-resistant and low-dielectric thermosetting adhesive of polyimide siloxane-epoxy resin-epoxy curing agent. 13. The flexible circuit board according to claim 12, wherein the adhesive is a thermosetting adhesive of polyimide siloxane-epoxy resin-epoxy curing agent having an epoxy resin-reactive group. 14. An adhesive provided by applying an adhesive solution to an aromatic polyimide film and then drying it.
14. The flexible circuit board according to claim 9, wherein an adhesive provided on the protective film is attached to the aromatic polyimide film. 15. The flexible circuit board according to claim 1, wherein the conductor is made of copper having a thickness of 8 to 50 μm.